New York City ranks No. 8 nationwide in infant mortality rates, with infant deaths dropping more than 60% since 1990, according to a "State of the World's Mothers" report issued by Save The Children.

With about 4.5 deaths for every 1,000 live births, "this is the lowest (rate of infant death) in history for New York," said Justin Mortensen, urban adviser for Save The Children, which crunched data from Kidscount and Measure of America in its report.

New York's performance however, is bittersweet, when put in a national context: While improvements have been made in infant morality worldwide over the last 15 years, the U.S. has tumbled to 33rd place out of 179 countries surveyed, with 6.1 infant deaths for every 1,000 births.

Las Vegas has the best rates in the U.S. for infant mortality (2.4%). The worst in the rankings of 50 cities is Cleveland (14.1%)

Local progress can be credited to improvements in prenatal care and eliminating barriers to health care, Mortensen said. He cited "simple policy prescriptions" such as the "Newborn Home Visiting Program," which provides breast feeding support and helps new moms in poor neighborhoods and the "Infant Mortality Reduction Initiative" as investments that have yielded results in NYC.

And there are still deep economic and racial disparities. African-American babies in Manhattan are five times more likely to die before their first birthday than white babies, for example, according to Save The Children.

And African-American women in New York City have a life expectancy of 80.1 years, compared to Asian women, who have an average life expectancy of 92 years. White women live an average of 83.4 years and Latinas clock in at 87.7 years.

The three leading causes of infant death in NYC in 2013 were prematurity (short gestation and low birth weight) (20.9%), followed by birth defects (20.3%) and cardiovascular disorders originating in the perinatal period (11.3%), according to data released this January by the NYC Department of Health and Mental Hygiene. External causes such as injuries, homicides contributed to 9.6% of deaths.

The U.S. also fares abysmally in maternal death rates, with an American woman more than 10 times as likely to die in pregnancy or childbirth than a Polish woman. Scandinavian countries such as Sweden, Norway and Finland have the best measures of maternal health, said Mortensen. "They have largely subsidized or free access to health care for most of their populations," and high levels of voluntary family planning, Mortensen said.